$f(t) = -2t+5$ $f\Big($
Answer: We need to solve an equation with the function's formula $-2t+5$ on one side and the given output $13$ on the other side. $\begin{aligned} -2t+5&=13\\\\ -8&=2t\\\\ -4&=t \end{aligned}$ Therefore, $f(-4)=13$.